Uust the other day I was in my room watching tv (and masturbating through my shorts) when my stepsister burst in as she usually does without knocking. I got my hand away pretty quick (or so I thought). She just said, 'I have to go to the bathroom,' and I didnt say anything.
I didn't think she had seen me, but then when she came out she looked over at me with a smile on her face and said, 'I know what you were doing.'
I said, 'Doing what?'
The she said, 'You were masturbating.'
And I said, 'No I wasn't.'
She said, 'I know you were. It's OK; I do it too sometimes.
I said, 'Oh yeah?'
She said, 'Yep.' she then said, 'Can I see you do it?'
I thought about it for a short while and said, 'If you promise not to tell anyone.' She agreed. Then I said, B'ut you have to get naked,' and she said only if I did. We both agreed so I toook off my shirt and shorts and was just in my boxers. Then she pulled her shirt off and unbuttoned and unzipped her pants and was standing there in a bra and panties. (She is 12 years old, almost 13, and has big boobs for her age.)
As she started to undo her bra, she stopped and told me to take my boxers off. I knew she could tell I already had a raging boner (7.5 inches),so I pulled my boxers down revealing my penis to her. All she said was, 'It's bigger than my brother's,' and before I could ask how she had seen her brother's,she told me she had accidentally walked in on him as well. She then took her bra off revealing her boobs to me. All that was left were the panties-not thong panties, but cute white ones with purple lining and a butterfly on the front.
She slowly pulled them down showing me a beautiful pussy that had obviously been shaved recently. She then said, 'Go ahead.' So I lay down on my bed and started going at it. After about thiry seconds she got in bed next to me and asked if she could try. So I took my hand off and she went at it. After about three minutes I had the best orgasm I have ever had shooting cum onto my chest. She then said, 'Do me.' So I reached over and went to work on her gorgeous vagina. She had an orgasm, then got up and thanked me, put her clothes back on, and went about her day like nothing happened, and I did the same. We have done this a few more times, each time getting better.